This invention relates to a nucleic acid sequence isolate from corn and to methods of using the sequence. In particular, the invention relates to a nucleotide sequence derived from the EPSP corn synthase gene which is capable of directing constitutive expression of a nucleic acid sequence that is operably linked to the EPSP corn synthase sequence.
The selection of a promoter in the genetic engineering of a gene is often a critical factor in obtaining expression of the desired gene. Promoters are typically found at the 5′ end of a gene which is either directly or indirectly recognized and bound by a DNA-dependent RNA polymerase during the initiation of transcription of the gene. Consequently, promoters play a major role in regulating gene expression. There are three general classes of promoters used in the genetic engineering of plants: 1) tissue specific promoters, 2) inducible promoters, and 3) constitutive promoters. Tissue specific or organ specific promoters drive gene expression is a certain tissue such as in the kernel, root, leaf, or tapetum of the plant. Chemicals or environmental stimuli such as heat, cold, or wounding induce inducible promoters. Although tissue specific and inducible promoters are required for certain applications, constitutive promoters are the most widely used promoters in the industry. Constitutive promoters are capable of driving a relatively high level of gene expression in most of the tissues of a plant. Constitutive promoters are particularly useful for producing herbicide tolerant plants. The most widely used constitutive promoter in the genetic engineering of plants is the CaMV 35S promoter. Other constitutive promoters include the maize polyubiquitin promoter and the rice actin promoter. In general, those familiar with the art agree that constitutive promoters that drive a high level of gene expression in most of the tissues of a plant are few in number and are of considerable value in the field of genetic engineering of crop plants.
Thus, it is desirable to develop additional constitutive promoters for use in plant transformation.